Generally, a refrigeration cycle is a thermodynamic cycle that absorbs heat from a cooling substance and transmits the absorbed heat to a heating substance. The most basic apparatus constituting the refrigeration cycle includes a compressor, a condenser, an expansion valve, and an evaporator.
The compressor serves to compress a refrigerant and discharge a high-temperature and high-pressure gas-phase refrigerant. The condenser serves to condense the high-temperature and high-pressure gas-phase refrigerant discharged from the compressor and make a normal-temperature and high-pressure or low-temperature and high-pressure liquid-phase refrigerant. The normal-temperature and high-pressure or low-temperature and high-pressure refrigerant is expanded while passing through the expansion valve, to thereby be changed into a low-temperature and low-pressure refrigerant. The expanded refrigerant is evaporated in the evaporator, and is further lowered in temperature and pressure. In the process of evaporation, the refrigerant draws heat from the surroundings, thereby cooling the surrounding air.
After completing a one-cycle circulation as described above, the refrigerant is returned to the compressor and compressed again, and the above described cycle is repeatedly carried out. The evaporator operates to draw heat from the surroundings and generate cooled air, namely, cold air. A refrigerator is configured to cool the interior of a cooling compartment by blowing the cold air into the cooling compartment under the operation of a fan.
Providing a conventional refrigerator, including a freezing compartment and a refrigerating compartment, with the above described refrigeration-cycle apparatus, an evaporator is installed in the freezing compartment to generate cold air having a temperature band required for the freezing compartment. In this case, the cooling of the refrigerating compartment is accomplished as a part of the cold air generated in the freezing compartment is supplied into the refrigerating compartment. A problem of this cooling manner is that the refrigerating compartment has a very uneven temperature distribution, and moreover, the temperature distribution of the freezing compartment also becomes uneven as the cold air is transmitted into the refrigerating compartment.
To solve the above described problem, there is the rise of the technology of independently controlling temperatures of the freezing compartment and the refrigerating compartment and providing the freezing compartment and the refrigerating compartment with an even temperature distribution.
The conventional refrigerator includes only the freezing compartment, serving as a cooling compartment of a relatively low-temperature band, and the refrigerating compartment serving as a cooling compartment of a relatively high-temperature band. Nowadays, there is the rise of the technology for a refrigerator including a variety of cooling compartments having different temperature bands from one another, for example, a cooling compartment having a medium temperature band between those of the refrigerating compartment and the freezing compartment, or a cooling compartment having a temperature hand higher than that of the refrigerating compartment, to satisfy the consumer's demand.